Outline drawings comparing the male reproductive tracks of four extant Partula species from the Mariana Islands. Male anatomy abbreviations are as follows: retractor muscle (RM), caecum (C), penis (P), vas deferens (VD), uterus (U). The figure of Partula langfordi is adapted from figure 5 of Kondo (1970). Note, Kondo found no difference between the male reproductive tracts of P. gibba and P. langfordi.